Cruz will indeed win the nomination on the second ballot should Trump fail to win it on the first ballot.
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This is an opinion piece but this is pure conjecture. If Trump is a few delegates short why is it more likely Ted can make up a several hundred delegate gap on the second ballot? Not addressed in the article one of many reason the article and title is is not convincing. This is a lifeline to Cruz supporters as Ted will be eliminated from the possibility of a first ballot victory by the end of the month. Trump will then become the presumptive nominee.
Because many delegates are released to vote their preference on subsequent ballots, to answer your question about the ‘delegate gap’. I’m not saying the majority of Rubio or Kasich delegates would go to Cruz, but they might, which is why the Trump folks’ claim that it will all be ‘over’ after New York is just as much wishful thinking as they say this article is for Cruz folks.